What can we learn from phi_1 and B_d^0 -> pi^+ pi^- ?

Abstract

We discuss what we can understand from ${\varphi }_1$ and $B_d^0\to {\pi }^{+}{\pi }^{-}$ decay mode. Using a convention without weak phases ${\varphi }_2$ and ${\varphi }_3$, we can solve the parameters from the time-depended CP asymmetry. If we can put a condition the contribution from penguin except for the CKM factor including in the diagram is small, then we can lead the allowed region of $R_t$ or ${\varphi }_2$ by using the convention.

Comments: 7 pages, 4 figures, references and comments added